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Biomedical subjects

G A van Zanten

Publications and source records attributed to G A van Zanten.

At least 19 recordsLinked to original sources
PubMed2006

A comparison of intra- versus post-operatively acquired electrically evoked compound action potentials.

The objective of this study was to compare the electrically evoked compound action potentials, intra- versus post-operatively, in cochlear implant patients. In a prospective study twenty-five consecutively implanted adult patients received a multichannel cochlear implant. In all patients, electrically evoked compound action potentials were recorded immediately after cochlear implantation and in a post-operative setting nine months later. The threshold of the electrically evoked compound action potential was determined in both settings. A high success rate (97.4%) was found in the intra-operative setting when recording the electrically evoked compound action potential threshold per patient. The success rate per patient was significantly lower (53.4%) in the post-operative setting. Correlations between the intra- versus the post-operative ECAP thresholds were statistically significant for all electrodes tested. The ECAP thresholds were not significantly different for the two settings. The intra-operative setting is preferable for acquisition of the ECAP threshold.

Action Potentials↗
PubMed2005

GATA3 haploinsufficiency causes a rapid deterioration of distortion product otoacoustic emissions (DPOAEs) in mice.

Human HDR (hypoparathyroidism, deafness and renal dysplasia)-syndrome is caused by haploinsufficiency of zinc-finger transcription factor GATA3. The hearing loss due to GATA3 haploinsufficiency has been shown to be peripheral in origin, but it is unclear to what extent potential aberrations in the outer hair cells (OHCs) contribute to this disorder. To further elucidate the pathophysiological mechanism underlying the hearing defect in HDR-syndrome, we investigated the OHCs in heterozygous Gata3-knockout mice at both the functional and morphological level. While the signal-to-noise ratios of distortion product otoacoustic emissions (DPOAE) in wild type mice did not change significantly during the first half-year of live, those in the heterozygous Gata3 mice decreased dramatically. In addition, both light microscopic and transmission electron microscopic analyses showed that the number of OHCs containing vacuoles was increased in the mutants. Together, these findings indicate that outer hair cell malfunctioning plays a major role in the hearing loss in HDR-syndrome.

Age Factors↗
PubMed2002

A pilot case control follow-up study on hearing in children treated with tobramycin in the newborn period.

OBJECTIVE: To assess the occurrence of hearing loss in children due to neonatal exposure to long courses of tobramycin and/or high tobramycin serum concentrations. METHODS: This was a pilot case-control study in 3-4-year old children. Data on tobramycin administration were abstracted from the patient files of an earlier study. Patients exposed in the neonatal period to either long courses (>7 days) or high serum concentrations of tobramycin constituted the study group. The control group consisted of patients without tobramycin exposure. Patients were matched for other risk factor according to criteria of the joint committee on infant hearing. All patients underwent the following investigations: otoscopy and pneumatic otoscopy, followed by impedance audiometry, to exclude middle ear effusion. Click-evoked oto-acoustic emissions (ce-OAE) as well as distortion product oto-acoustic emissions (dp-OAE), tested at f2 frequencies ranging from 1 to 10 kHz, were measured to assess hearing. All patients with abnormal ce-OAE results underwent brainstem electric response audiometry (BERA) as well. Since aminoglycoside ototoxicity is usually bilateral, results were compared per patient and not per ear. RESULTS: A total of 29 patients were tested. Eleven patients were excluded due to middle ear effusion. Data for 18 patients were analyzed. In the tobramycin treated group (n=9) both ce-OAE and dp-OAE (at all tested frequencies) were not detectable in six ears of three patients. All other patients had normal ce-OAE's as well as normal dp-OAE's in this frequency range. Difference between the tobramycin treated and control group for OAE as well as dp-OAE showed a trend (P=0.08). In all three patients with undetectable emissions BERA confirmed a cochlear loss of 60-70 dB at 3 kHz in both ears. These three patients had the longest total exposure to tobramycin: 20-24 days and 84-92 mg/kg, respectively. No relation to either peak or trough serum concentrations could be detected. CONCLUSION: There was no statistical relation between hearing loss and tobramycin exposure, probably due to sample size. Our results do indicate a need for a case-control follow-up study of hearing in neonates exposed to long courses of aminoglycosides.

Acoustic Impedance Tests↗
PubMed2001

Costs of different strategies for neonatal hearing screening: a modelling approach.

OBJECTIVE: To compare the cost effectiveness of various strategies for neonatal hearing screening by estimating the cost per hearing impaired child detected. DESIGN: Cost analyses with a simulation model, including a multivariate sensitivity analysis. Comparisons of the cost per child detected were made for: screening method (automated auditory brainstem response or otoacoustic emissions); number of stages in the screening process (two or three); target disorder (bilateral hearing loss or both unilateral and bilateral loss); location (at home or at a child health clinic). SETTING: The Netherlands TARGET POPULATION: All newborn infants not admitted to neonatal intensive care units. MAIN OUTCOME MEASURE: Costs per child detected with a hearing loss of 40 dB or more in the better ear. RESULTS: Costs of a three stage screening process in child health clinics are 39.0 pounds (95% confidence interval 20.0 to 57.0) per child detected with automated auditory brainstem response compared with 25.0 (14.4 to 35.6) pounds per child detected with otoacoustic emissions. A three stage screening process not only reduces the referral rates, but is also likely to cost less than a two stage process because of the lower cost of diagnostic facilities. The extra cost (over and above a screening programme detecting bilateral losses) of detecting one child with unilateral hearing loss is 1500-4000 pounds. With the currently available information, no preference can be expressed for a screening location. CONCLUSIONS: Three stage screening with otoacoustic emissions is recommended. Whether screening at home is more cost effective than screening at a child health clinic needs further study.

Audiometry, Evoked Response↗
PubMed1996

Neonatal hearing screening.

UNLABELLED: Severe congenital hearing impairment is an important handicap affecting 0.1% of live-born infants and 1%-2% of graduates of Neonatal Intensive Care Units. The prognosis for intellectual, emotional, language and speech development in the hearing-impaired child is improved when the diagnosis is made early and intervention is begun before the age of 6 months. The usual age at diagnosis of hearing impairment is at least 18-30 months (or even later in cases of less severe hearing impairment) where there are no screening programmes. When screening is carried out using distraction methods at the age of approximately 9 months some hearing-impaired infants are missed and those discovered are at least 15-18 months before intervention begins. Neonatal screening could give hearing-impaired children the best chances for optimal care and development. Universal neonatal hearing screening is necessary, because, when neonatal hearing screening is restricted to high risk groups 30%-50% of infants with hearing loss are not discovered. The methods available for neonatal hearing screening are discussed in this paper. CONCLUSION: In our view automated measurement of auditory brainstem responses is the most valuable method for universal neonatal hearing screening.

Audiometry, Evoked Response↗
PubMed1993

Hearing and language in preschool very low birthweight children.

To get more insight into preschool language and hearing in high-risk very low birthweight (VLBW) children, we conducted a prospective study in a cohort of 79 children. The prevalence of language impairment and hearing loss at age 3-4 years, their relationship to each other as well as to perinatal conditions, neurodevelopmental outcome and the home environment are described. Mild hearing loss was found in 26%, moderate hearing loss in 13% and severe hearing loss in 3% of the children. None of the children was deaf. Abnormal tympanometry was found in 57% of the children. Hearing loss at age 4 years was related to a less optimal neonatal condition and was not related to the obstetrical condition or to neonatal cerebral ultrasound findings. Language impairment was found in 21% of the children at age 3.6 years. Receptive and expressive language was not related to perinatal conditions. There was no relation between the language assessments and the audiological assessments. Cognition and the home environment of the child were the only independent variables in the prediction of language in preschool VLBW children.

Audiometry, Evoked Response↗
PubMed1993

Aspects of spontaneous otoacoustic emissions in healthy newborns.

Spontaneous otoacoustic emissions (SOAEs) are pure-tone like signals, spontaneously present in the ear canal. In normal adult ears the prevalence of SOAEs is reported to be 30-70%, probably depending on the noise floor of the recordings. In infant studies, results on the SOAE prevalence are rare. SOAEs as well as evoked otoacoustic emissions (EOAEs) were recorded in healthy newborns. Their ages varied between 1 and 10 days. The recordings were done with commercially available equipment in a separate not sound treated room of the obstetric department. The prevalence of SOAEs was 78%, which is higher than previously reported for adults as well as healthy newborns. The prevalence was not significantly different between left and right ears, or genders. The number of emissions per emitting ear amounted on average 5.5. The median number of SOAEs in boys (3.3) is significantly lower than in girls (4.6). The SOAE levels were between -2 and 42 dB SPL. The mean level per emitting ear was 8.0 dB SPL and not significantly different between right and left ears or genders. However, the level of the strongest emission per emitting ear was significantly higher for right than for left ears. In contrast with adults most of the emissions (70%) are at frequencies above 2 kHz. Comparing the levels of the EOAEs between ears with and without SOAEs we found a statistically significant higher EOAE level in ears with SOAEs. This supports our previous hypothesis that the higher EOAE level found in healthy newborns is partly due to the more frequent presence of stronger SOAEs in healthy newborns.(ABSTRACT TRUNCATED AT 250 WORDS)

Evoked Potentials, Auditory, Brain Stem↗
PubMed1993

Frequency-specific aspects of the auditory brainstem response threshold elicited by 1000-Hz filtered clicks in subjects with sloping cochlear hearing losses.

The frequency specificity of the ABR threshold evoked by a 1000-Hz filtered click was determined in subjects with sloping cochlear hearing losses, both high- and low-frequency in character. The results show that the ABR threshold evoked by this stimulus is low-frequency specific. The standard error in estimating the 1000-Hz pure-tone threshold (PTT) is 10.4 dB, which equals that for estimating the 3000-Hz PTT from the routinely used click-evoked ABR threshold. The ABR threshold evoked by a 1000-Hz filtered click can therefore be regarded as an accurate tool to predict the pure-tone hearing loss at 1000-Hz. In comparison with the ABR threshold evoked by a click masked with 1590-Hz high-pass noise, the ABR threshold evoked by a 1000-Hz filtered click has a larger dynamic range, yields a larger number of useful responses and is less time consuming. For clinical low-frequency-specific ABR threshold assessment, the 1000-Hz filtered click is therefore preeminently useful.

Adolescent↗
PubMed1992

Growth of evoked otoacoustic emissions during the first days postpartum. A preliminary report.

Evoked otoacoustic emissions (EOAEs) were recorded twice in 20 ears of 15 newborns. The recordings were performed in a room of the well baby ward, using the ILO88 in its default setting, i.e. with click stimulation. On the first test occasion, the infants were between 3 and 51 h of age, and EOAEs were identified in 10 ears. On the second test occasion, while the infants were at least 1 day older (range 42-107 h), EOAEs were present in all ears. The second EOAE was stronger, so the EOAE appeared to grow in the first days postpartum. This might be due to middle ear clearance of amniotic fluid, shortly after birth. The results of the EOAEs of the second examination were compared with 10 EOAEs in adult ears. The response levels of the newborns were significantly higher than in the adults. The (cross)-correlation peak value of the two tests' waveforms is over 0.75, however sometimes only after filtering around the most pronounced emission frequencies. The study proves that newborns failing the EOAE screen in the first 24 h after birth can pass if retested 1 day later, simply because of growth of EOAE strength.

Acoustic Stimulation↗
PubMed1992

Low-frequency specificity of the auditory brainstem response threshold elicited by clicks masked with 1590-Hz high-pass noise in subjects with sloping cochlear hearing losses.

In this study, the frequency specificity of the ABR threshold to stimulation with a click masked with 1590-Hz high-pass noise was determined in subjects with sloping cochlear hearing losses both high- and low-frequency in character. The results show that the ABR threshold elicited by this stimulus is low-frequency specific. The standard error in estimating the 1,000-Hz pure-tone threshold from the high-pass-noise-masked click-evoked ABR threshold is 10.2 dB which equals that for estimating the 3,000-Hz pure-tone threshold from the routinely used unmasked click ABR threshold. The ABR threshold elicited by a click masked with 1590-Hz high-pass noise can therefore be regarded as an accurate tool to predict the pure-tone hearing loss at 1,000 Hz. However, this method is less suitable for routine clinical testing because of the masking noise needed: the occasional high loudness level adversely affects the response quality and reduces the dynamic range of pure-tone hearing losses to be assessed. A third disadvantage is that determining the masking level electrophysiologically for each ear is time consuming. The search for a method with no or less masking noise should therefore continue.

Acoustic Stimulation↗
PubMed1992

Comparison between the frequency specificities of auditory brainstem response thresholds to clicks with and without high-pass masking noise.

In this study, the frequency specificity of the auditory brainstem response (ABR) threshold to a click masked with 1590-Hz high-pass masking noise is compared with the frequency specificity of the unmasked click-evoked ABR threshold. The ABR threshold to the high-pass-noise-masked click stimulus is low frequency specific and corresponds with the 1,000-Hz pure-tone threshold. Although the ABR threshold to the unmasked click stimulus corresponds with the '3,000'-Hz pure-tone threshold, the frequency specificity seems much less pronounced than that of the low-frequency-specific stimulus. This study shows, however, that this apparent lack of frequency specificity can be attributed to the selection of pure-tone hearing losses. The ABR threshold evoked by an unmasked click stimulus is, therefore, preeminently useful as a high-frequency point of a two-point audiogram. The possible reasons why the ABR threshold evoked by a broad-band stimulus as the unmasked click corresponds with the higher frequencies of the pure-tone audiogram are discussed.

Acoustic Stimulation↗
PubMed1992

Hearing loss in middle-age persons with Down syndrome.

Hearing function of 35 institutionalized persons with Down syndrome, age 35 to 62 years, was assessed by means of otoscopy, impedance audiometry, brainstem evoked response audiometry, and pure tone audiometry. Using brainstem evoked response audiometry, we determined response thresholds for 59 ears, which compares favorably with pure tone audiometry (20 ears). We found hearing losses of 20 dB to over 90 dB in 56 of these ears. Hearing loss should be considered and, whenever feasible, excluded as a contributing factor in social and mental deterioration in middle-age persons with Down syndrome.

Acoustic Impedance Tests↗
PubMed1990

Frequency specificity of the auditory brainstem response elicited by 1,000-Hz filtered clicks.

In normal-hearing subjects and in subjects with a flat cochlear hearing loss, auditory brainstem responses (ABR) were recorded at various levels of a 1,000-Hz filtered click stimulus with and without high-pass filtered masking noise. The difference in latency of the major peak in the ABR for the masked and unmasked condition was zero at the ABR threshold. We regard this as proof of the frequency specificity of the 1,000-Hz filtered click-stimulated ABR threshold. The difference between ABR threshold and the subjective puretone threshold at 1,000 Hz amounted to 19 dB in normal-hearing subjects and to 10 dB in subjects with a flat cochlear hearing loss. This is probably related to loss of temporal integration and an abnormal loudness growth (recruitment).

Acoustic Stimulation↗
PubMed1990

Monaural versus binaural auditory brainstem response threshold to clicks masked by high-pass noise in normal-hearing subjects.

Monaural and binaural auditory brainstem response (ABR) thresholds to clicks masked by high-pass noise with a cut-off frequency of 1,590 Hz were measured in normal-hearing subjects. In sleeping normal-hearing subjects, the 1,000-Hz frequency-specific ABR threshold for binaural stimulation amounted to 12 dB nHL and for monaural stimulation to 18 dB nHL. No significant difference in latency was found between monaural and binaural stimulation. Binaural ABR threshold was 5.5 +/- 1.4 dB (mean +/- SEM) lower than the mean monaural ABR threshold. This difference is statistically significant (Student's t test; p less than 0.005).

Acoustic Stimulation↗
PubMed1989

Brainstem electric response audiometry: estimation of the amount of conductive hearing loss with and without use of the response threshold.

Three aspects of brainstem response audiometry were investigated in the present study. (1) The brainstem response threshold was compared with the pure-tone audiogram in 40 patients with conductive hearing loss. The brainstem response threshold has a one-to-one relationship with the mean of the pure-tone thresholds at 2 and 4 kHz. The correlation coefficient in this comparison is 0.84 and the standard error of the estimate is 8.3 dB. Taking into account corresponding results in cochlear hearing loss [Drift et al.: Audiology 26: 1-10, 1987] it is concluded that the brainstem response threshold provides a good estimate of the amount of peripheral hearing loss, independent of the type of hearing loss. (2) It was shown [Drift et al.: Audiology 27: 260-270, 1988] that different types of peripheral hearing loss can be distinguished reliably with brainstem response audiometry. Parameters relevant for this distinction were the horizontal shift of the latency-level curve (1(L) curve), that of its derivative and the response threshold. In the clinical situation measurement of the response threshold is not always possible due to restlessness of the patient. To simulate this situation we randomly truncated the lower parts of the 1(L) curves of quiet patients. The test group consisted of 22 adult normally hearing subjects, 79 patients with cochlear hearing loss, 40 with conductive hearing loss and 22 with mixed hearing loss. Linear discriminant analysis was applied to the horizontal shift of the 1(L) curve and of its derivative. The brainstem diagnosis 'normal hearing' correctly excludes a conductive hearing loss in 98% of the cases and the brainstem diagnosis 'cochlear hearing loss' does so in 79%. The brainstem diagnosis 'conductive hearing loss' correctly predicts a conductive component of hearing loss in 94% of the cases and the brainstem diagnosis 'mixed hearing loss' does so in 90%. The distinction between cochlear hearing loss and normal hearing is not reliable, neither is the distinction between conductive and mixed hearing loss. (3) The amount of the conductive component of hearing loss can be estimated by the horizontal shift of the 1(L) curve. Statistical comparison with the mean of the air-bone gaps at 2 and 4 kHz gave a correlation coefficient of 0.77, a standard error of the estimate of 9.7 dB, and a slope of the regression line of 0.93. An overestimation of about 7 dB has to be taken into account in case of mixed hearing loss.

Adolescent↗
PubMed1988

Brainstem electric response audiometry in preterm infants.

In the Sophia Children's Hospital in Rotterdam 108 preterm infants were examined with Auditory Brainstem Response (ABR). Ears were categorized as 1) normal sensitivity for post-conceptional age (PCA), 2) probably-mild loss of sensitivity, or 3) a moderate to severe loss of sensitivity. All infants showed ABR peaks, so no "deaf" individuals were found. A bilaterally normal sensitivity was found in 61. A probably-mild loss was found in 22 infants and a moderate to severe loss in 21 infants. The type of loss was conductive in 31 and cochlear in 12. A moderate to severe bilateral cochlear loss was found in 2. This is in line with the literature. Of the 43 infants with a (probable) loss 18 were examined again at 3 months corrected age. Only half of the conductive losses had disappeared, the other half was exacerbated. About 2 out of 3 initially moderate to severe losses were confirmed at follow-up. The moderate to severe losses of the cochlear type were all confirmed.

Audiometry, Evoked Response↗
PubMed1987

The relation between the pure-tone audiogram and the click auditory brainstem response threshold in cochlear hearing loss.

Auditory brainstem response thresholds for 209 ears with cochlear hearing loss were compared with the pure-tone thresholds. It is shown that the pure-tone threshold in the 2- to 4-kHz region has a one-to-one relationship with the auditory brainstem response threshold. Estimating the pure-tone threshold from the auditory brainstem response threshold, the standard error of the estimate is 11 dB. A small part of this estimation error is due to errors in the measurement of the auditory brainstem response threshold and the mean of the pure-tone thresholds at 2 and 4 kHz. The major part is due to unknown factors that are involved in the physiological relationship between the two thresholds.

Audiometry↗